Q: A bag contains 5 red, 3 blue, and 2 green marbles. If two marbles are drawn without replacement, what is the probability that both are red?

$$P = \frac{5}{10} \times \frac{4}{9} = \frac{20}{90} = \frac{2}{9}$$

Q: A student wants to know the percentile rank of a test score of 75 in a class of 40 students. If 30 students scored below 75, what is the percentile rank?

$$P = \frac{30}{40} \times 100 = 75\%$$

Question 1

Which of the following is an example of data measured at the interval level?

Accepted Answer

The temperature in Celsius recorded each hour during a day.

Question 2

A researcher wants to study the average commute time for employees at a large company. She divides the employees into departments and randomly selects 5 employees from each department. Which sampling method is she using?

Accepted Answer

Stratified sampling

Question 3

Which of the following best describes continuous data?

Accepted Answer

The height of students measured in centimeters.

Question 4

Given the following frequency distribution for exam scores:

Class: 60-69, Frequency: 3
Class: 70-79, Frequency: 7
Class: 80-89, Frequency: 10
Class: 90-99, Frequency: 5

What is the class midpoint for the class 80-89?

Accepted Answer

$$\frac{80+89}{2} = 84.5$$

Question 5

A frequency histogram is constructed for a set of test scores. Which of the following is NOT a correct guideline for constructing the histogram?

Accepted Answer

Leave gaps between the bars to show separation between classes.

Question 6

Given the following data: 4, 7, 8, 10, 12. What is the midrange?

Accepted Answer

$$\frac{4+12}{2} = 8$$

Question 7

A distribution of test scores is described as 'skewed right.' Which of the following statements is most accurate?

Accepted Answer

The mean is greater than the median.

Question 8

Given the following frequencies and midpoints for a frequency distribution:

Midpoints: 10, 20, 30
Frequencies: 2, 5, 3

Calculate the mean using the formula $$\bar{x} = \frac{\sum(f \cdot x)}{\sum f}.$$

Accepted Answer

$$\bar{x} = \frac{(2 \cdot 10) + (5 \cdot 20) + (3 \cdot 30)}{2+5+3} = \frac{20+100+90}{10} = \frac{210}{10} = 21$$

Question 9

A student scored 85 on a test where the mean was 80 and the standard deviation was 5. What is the student's z-score?

Accepted Answer

$$z = \frac{85 - 80}{5} = 1$$

Question 10

If the standard deviation of a data set is 4, what is the variance?

Accepted Answer

$$4^2 = 16$

Question 11

A hospital records the blood types of 100 patients. Which level of measurement is used for blood type?

Accepted Answer

Nominal

Question 12

A lottery randomly selects 1 winner from every 100th ticket sold. Which sampling method is this?

Accepted Answer

Systematic sampling

Question 13

In a class of 30 students, 12 are male and 18 are female. If one student is selected at random, what is the probability that the student is female?

Accepted Answer

$$P = \frac{18}{30} = 0.6$$

Question 14

A bag contains 5 red, 3 blue, and 2 green marbles. If two marbles are drawn without replacement, what is the probability that both are red?

Accepted Answer

$$P = \frac{5}{10} 	imes \frac{4}{9} = \frac{20}{90} = \frac{2}{9}$$

Question 15

A survey asks people to rate their satisfaction on a scale from 1 (very dissatisfied) to 5 (very satisfied). What level of measurement is this?

Accepted Answer

Ordinal

Question 16

A student wants to know the percentile rank of a test score of 75 in a class of 40 students. If 30 students scored below 75, what is the percentile rank?

Accepted Answer

$$P = \frac{30}{40} 	imes 100 = 75\%$$

Question 17

A distribution of ages in a population is bell-shaped. Which statement is true?

Accepted Answer

The mean, median, and mode are approximately equal.

Question 18

A student’s z-score is -2.5. What does this indicate about the student’s score?

Accepted Answer

The score is significantly low compared to the mean.

Question 19

A deck of cards has 52 cards. What is the probability of drawing an ace or a king in a single draw?

Accepted Answer

$$P = \frac{4}{52} + \frac{4}{52} = \frac{8}{52} = \frac{2}{13}$$

Question 20

In a group of 20 people, the probability that at least one person has type O blood is closest to:

Accepted Answer

1 minus the probability that none have type O blood

Introductory Statistics: Exam 1 Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard